Shell manipulation: interactive alteration of multiple-material fuzzy structures

Shell rendering uses a recently described data structure, called a shell, for representing semi- transparent volumes. The shell is a generalization of the semi-boundary representation used for fast visualization, manipulation, and analysis of binary volumetric objects. Shell manipulation is an extension of the previously developed manipulation operations on binary objects to fuzzily defined objects. The paper describes algorithms for plane and curved cut-away, separation, and segmental movement operations. These operations are done interactively on volume renditions of the objects in a standard workstation environment using portable software.